The present invention relates to an apparatus and a method in which an optical module including a lead frame and optically operating members such as a light emitter and a light receiver is manufactured through the use of dies. In addition, the present invention also relates to a clamper for clamping optically-operating members such as a light emitter and a light receiver and a lead frame for an optical module when connecting wires to the members and the frame.
A conventional method of manufacturing an optical module, in which optically operating members which are a light emitter E/O and a light receiver O/E, for example, and connected to electronic circuits with wires W, as shown in FIG. 7, and a lead frame L/F are set in dies and then integrally molded with a resin, has been proposed. The method includes a wire bonding step in which the optically operating members and the electronic circuits formed on the lead frame are connected with the wires w of aluminum by a wire bonder, and a molding step in which a workpiece having the members, the circuits, the wires connected to them, and the lead frame is set in the dies and then integrally molded with the resin.
Since the lead frame L/F coupled to the light emitter E/O and the light receiver O/E with the wires W is picked up and carried with tweezers during the manufacturing of the optical module in the conventional method, as shown in FIG. 7, the weight of the light emitter and that of the light receiver act on the wires so that it is likely that excessive stress is caused in the wires and the optically operating members are put out of a prescribed positional relationship to break or cut off the wire to lower the reliability or yield of the optical module.
In addition, in a conventional apparatus for manufacturing the optical module, a means for conveying the workpiece to the wire bonding section, and a means for conveying the workpiece to the dies of the molding section are provided separately from each other. For that reason, a workman needs to manually transfer the workpiece from a workpiece clamper for the wire bonding section to a conveyance pallet after the connection of the wires to the members and the frame and then transfer the workpiece from the pallet to the dies of the molding section. Since the members and the frame coupled thereto with the wires are not accurately fixed in a positional relationship, the aluminum wires are stressed during the transfer to make it likely that the strength of the wires falls to make them defective after the transfer. For that reason, the workpiece needs to be removed and set before and after the conveyance as the members and the frame remain accurately kept in the positional relationship. If the dies are very high in accuracy, it is difficult to set the members and the frame in the positional relationship in the dies as accurately as them. For that reason, it is necessary to realize a degree of freedom for coping with the inaccurate setting of the members and the frame in the dies. Since the transfer is performed through batch processing, the transfer is not appropriate for a single-unit-flow production line, and makes it necessary to prepare a large number of pallets for temporary-storage.
Further, an optical module manufacturing art, in which optically operating members which are a light emitter and a light receiver, for example, and a lead frame coupled to the members with wires are set in dies and then integrally molded with a resin to constitute an optical module, has been proposed. FIG. 13 is a perspective view of a workpiece having the light emitter E/O, the light receiver O/E and the lead frame L/F coupled to them with the wires W. The lead frame L/F includes a peripheral portion, islands, and inner and outer lead pins. Electronic circuit elements mounted on the islands constitute electronic circuits which are a light emission circuit and a light reception circuit. The optically operating members E/O and O/E, and the inner lead pins are connected to the electronic circuits C with the wires W. The optical module is manufactured by taking a wiring step in which the electronic circuits C are connected to the optically operating members E/O and O/E and the inner pins by the wires W of aluminum, a die-setting step in which the workpiece having these module components connected with the wires is set in the dies, and a molding step in which the resin is injected into the dies so that the components are integrally molded with the resin.
A conventional clamper for the wiring step includes a block 101, and a cover 102, as shown in FIG. 14. The block 101 has V-shaped-cross-section grooves 101a, in which the optically operating-members E/O and O/E are positioned, and a clamping surface 101b, to which the lead pins of the members and the lead frame L/F are clamped on the same plane. The cover 102 has V-shaped-cross-section grooves 102a whose positions correspond to those of the grooves 101a of the block 101 and which are for holding the members E/O and O/E, and an opening 102b at which the wire-connected portions of the inner lead pins and islands of the lead frame L/F and the lead pin ends of the members are exposed. The lead frame is pinched between the block 101 and the cover 102 so that the frame is clamped. The portions of the inner lead pins of the lead frame clamped on the clamping surface 101b of the block 101 and the ends of the lead pins 103 of the members E/O and O/E clamped on the surface are connected to the wires W by an ultrasonic wire bonder, as shown in the part (a) of FIG. 15. The bonder destroys the oxide films of the surfaces of the connected parts of these components by ultrasonic vibration energy to connect them to each other.
Since the positioning grooves 101a of the conventional clamper and the clamping plane surface 101b thereof are in a fixed positional relationship, the optically operating members E/O and O/E and the lead frame L/F cannot properly be clamped by the clamper for the connection of the wires W if the end of the lead pin 103 of the member is fused and coupled in a wrong position to the body of the member due to the failure in the optical centering of the member during the assembly thereof, as shown in the other parts (b) and (c) of FIG. 15. If the end of the lead pin 103 is fused and coupled in an upper wrong position as shown in the part (b) of FIG. 15, a gap is made between the pin and the clamping surface 101b so that the wire W cannot be connected to the end of the pin by the wire bonder. If the end of the lead pin 103 is fused and coupled in a lower wrong position as shown in the part (c) of FIG. 15, the pin is bent at the time of the pushing-down of the member with the cover 102 so that the pin-secured portion of the member is damaged or the wire W cannot be connected to the pin.
Besides, when the workpiece having the optically operating members, the lead frame and the wires connected to them is taken out from the clamper, the wire is likely to be stressed to be damaged.
Since the wire bonder is kept from coming into contact with the cover 102 when the bonder is put in contact with the wire-connected portion of the lead frame L/F, the frame cannot be clamped near the portion by the cover. For that reason, the inner lead pin of the frame is not clamped strongly enough, at the time of the connection of the wire W to the pin, to effectively transmit ultrasonic waves from the wire bonder to the wire-connected portion. This results in lowering the yield of the connection of the wire.